Large area optical retroreflectors are sometimes made of small glass spheres embedded in epoxy, and oftentimes just bonded to a carrier by means of this epoxy. These retroreflectors are usually available as generally planar tapes or sheets with adhesive backing. The retroreflective properties of such tapes are such that they reflect incident radiation back within a very small angular range around the direction of incidence. Such retroreflectors are very efficient and have a high reflectance in the direction of the irradiating source while in other directions very little radiation is scattered. One problem with these retroreflectors is that their efficiency of reflectance is dependent on the angle of the incoming rays with respect to the normal to the nominal reflector surface. Once a critical angle is exceeded, the reflectance substantially decreases. A typical glass sphere retroreflector has almost unchanged reflectance out to about 45.degree. from the normal to the reflector surface but drops quickly to very low values beyond that angle. Thus, such retroreflectors are not useful when the incident light is expected to come from a source which may be at a wide angle from the normal. Accordingly, there is need for reflectors which are efficient over a wide angular range of incident radiation.